clarify usage of 'bean' term usage in the spec

We should go to the spec and look up all 'bean' words as they are 5 different meaning the word 'bean' is used for

• The Bean<T> extends Contextual<T>. Should be referred as 'Bean' or 'CDI Bean'
• The class which gets scanned. Should be referred as 'Bean Class' to
• The instance stored in the context. Should be referred to as 'Contextual Instance'
• The proxy for a Contextual Instance should be referred to as 'Contextual Reference'
• The type of an injection point should be referred to as 'InjectionPoint Type'